1. Field of the Invention
The present invention relates to a process and apparatus for blow molding thermoplastic resins, particularly for obtaining hollow bodies such as bottles and the like.
2. Prior Art
Extrusion blow molding techniques for hollow bodies habitually suffer from serious limitations and drawbacks. Thus, in the case of injection and blow molding, irregularities occur in the weight and gauges, in welds, in material to be recycled and in the gauging of the bottle neck, the result being products of poor strength and finish.
In the case of biorientated injection and blow molding with cores and preforms, contemplated in Spanish patent No. 505.091, it is not feasible to obtain containers with handles, narrow necks or flattened bodies, nor is it possible to vary the weight, once set. In preforms of great thickness, it is difficult to homogenize the temperature thereof to heat condition the material, whereby in certain cases a prior cooling or heating is necessary. This is costly in energy, requires more time and installations of certain complexity.